I can use the very same argument: why bother with creating a separate file and go through all the oddities of linking it together with the C part?
1) what oddities?
2) why put an assembler function in a C module

I see no indication in the original post that this was the intention. Nor do I remember a post requiring this - but I admit I am not member of this Forum for that long time as others here may be.
I do, most posts re assembler in C have been about doing some 'crummy' thing that would give the compiler hiccups.

Erik